The 49-year-old actor - who previously won an Academy Award for his portrayal of music star Ray Charles - has agreed a deal to star as the New York-born icon, whose career was blighted by numerous controversies.

A source said: ''Jamie went to a couple of sessions with his trainer in the gym for this movie.

''He looked quite good throwing a few jabs and crosses against the pads. But when he tried a bit of sparring, he didn't fare so well.

''He took a couple of hooks and walked out. He knows if he wants to play Iron Mike then he needs to improve that side of his game.''

Legendary director Martin Scorsese is reportedly keen to helm the project, while Mike has also given Jamie a helping hand with his preparations.

The insider told The Sun newspaper: ''Mike knows it is Jamie's dream to play him and they have talked about gym work and how he could put him through his paces.

''The only thing is that if they go sparring and Mike connects, Jamie may never make any movie again.''

MIke, 51, is still the youngest heavyweight champion in boxing history.

But he was also convicted of rape in 1992, and banned from the sport after biting a chunk out of his rival Evander Holyfield's ear.

Looking forward to the new movie, Mike recently admitted: ''A lot of people aren't going to like the things I've done in my life.''